In the manufacturing of a semiconductor device, various kinds of apparatuses are used to conduct a process such as an oxidation, a diffusion, CVD (Chemical Vapor Deposition) and so on, to an object to be processed, for example, a semiconductor wafer. As one of them, a longitudinal type of thermal processing apparatus that is capable of conducting a thermal process to a plurality of objects to be processed at one time is known.
This longitudinal type of thermal processing apparatus is generally provided with a processing container made of quartz having an opening part at a lower end thereof. A holder for holding a plurality of objects to be processed is contained in the processing container. The opening part is dosed hermetically by a lid, and the plurality of objects to be processed are heated by a heating unit provided around the processing container, and thus a predetermined thermal process is conducted under a predetermined process-gas atmosphere (for example, refer to Japanese Patent Laid-Open Publication No. 2003-257958).
FIG. 10 represents a magnified cross-sectional view of a main part of a conventional longitudinal type of thermal processing apparatus. A processing container 102 shown in FIG. 10 has an opening part (a furnace opening) 103 at a lower end thereof and a flange portion 104 at a periphery of the lower end. The flange portion 104 is supported by a flange holder 105 made of a metal. An opening end 102a (a lower end) of the processing container 102 is made to come in contact with a lid 108 so as to be closed. The lid 108 is made of a metal, for example, a stainless steel. An O-ring 160 made of a heat-resistance resin is fitted on a fitting groove 161 of the lid 108 as an airtight material in order to seal between the lid 108 and the opening end 102a of the processing container 102.